In competitive running and personal recreation applications, a person wearing or using a mobile device may use satellite positioning platforms, including global positioning satellite (GPS) systems, to track location and speed. In some mobile devices, device speed may be calculated from Doppler shifts in the carrier wavelengths of received positioning signals. In these Doppler-enabled devices, the shift in carrier wavelength of the set of positioning signals due to the relative motion of the device as compared to the motion of the set of GPS satellites can be used to determine a speed of the device.
At times, however, the signals from GPS satellites can be obscured by trees, buildings, weather, or other types of interference or obstructions. When Doppler GPS tracking is degraded, the speed value that is output by the device tends to be reduced to a significant degree. The resulting speed value may not reflect or even reasonably approximate the user's true speed during those conditions. Users may not have a positive experience with speed tracking services that generate invalid speed values at unpredictable times due to signal degradation.
There is an opportunity to provide methods and systems for generating compensated speed values for a Doppler-enabled device, in which a value of a user's speed while running or performing other activities can be generated during degraded Doppler GPS conditions while maintaining a comparatively high degree of accuracy.